As means for improving properties and, specifically, gas-barrier property of various plastic base materials, there has been known an art of forming an inorganic barrier layer of a silicon oxide or the like by vacuum evaporation on the surfaces of the plastic base materials (patent document 1).
In a variety of electronic devices that have been developed and put into practice in recent years, such as organic electroluminescent (organic EL) devices, solar cells, touch panels, e-papers and the like, that must avoid leakage of electric charges, it is a requirement to impart a high degree of water-barrier property to the plastic base materials forming the circuit boards or to the films sealing the circuit boards. However, the inorganic barrier layer formed as described above is not still capable of meeting a high degree of requirement for attaining the water-barrier property. Therefore, a variety of proposals have been made for improving the water-barrier property.
A patent document 2, for example, proposes a gas-barrier laminate comprising an inorganic barrier layer formed on the surface of a plastic base material, and a sealing layer formed on the inorganic barrier layer, the sealing layer being dispersed with nanoparticles of a metal oxide or carbon nanotubes as a moisture-absorbing agent.
A patent document 3 proposes a gas-barrier laminate (film) comprising an organic layer, an inorganic barrier layer and a water-trapping layer formed on a base film, the water-trapping layer being formed of a moisture-absorbing polymer (concretely, a polyamide) or being formed by dispersing a moisture-absorbing material such as silica gel or aluminum oxide in a polymer binder such as a resin that can be cured with electron rays or ultraviolet rays.
Further, a patent document 4 proposes a gas-barrier laminate comprising a gas-barrier film and a moisture-absorbing layer formed by vacuum evaporation on the surface of a plastic base material, the moisture-absorbing layer containing an alkylene oxide, acrylate nanoparticles or an organometal complex.
Moreover, patent documents 5 to 7, which are filed by the present applicant, are proposing gas-barrier laminates obtained by forming a water-trapping layer on an inorganic barrier layer on a plastic base material, the water-trapping layer being the one obtained by dispersing a specific granular moisture-absorbing agent in the matrix of an ionic polymer.
In order to improve the water-barrier property to a high degree as described above, there have been proposed laminates of various layer constitutions combining the inorganic barrier layer and the water-trapping layer (moisture-absorbing layer, water-trapping layer, etc.) together. The above water barrier laminates are capable of exhibiting a high degree of barrier property against the water that flows in the direction of thickness (in the direction of surface) of the laminate but are not still capable of exhibiting the barrier property to a sufficient degree against the water that flows in from the side surfaces (end surfaces) thereof. Besides, no study has so far been conducted concerning the water that flows in from the end surfaces.